Hi, what oil is best for these Y blocks.
I read somewhere that modern oils reduce the issues the Y blocks had with getting oil up to the rockers?

Thanks,

 

Correct. Modern oil has a much better detergent/dispersant package{s} than period oils. But the main problem was oil galleys being mis-drilled on these engines, something you need to correct during a rebuild.

Is it a period or recently re-done engine?

 

Hi, I'm not sure of the history.
I just want to test it initially. I recently used diesel and WD40 in the cylinders to unsieze the engine. So I dropped the oil.

A synthetic 10W40 is ok?

Thanks,

 

So it is an older engine, no reman and/or upgrades?

A 10W-40 SYN (Blend will keep initial cost down) will be OK (IMO). It will be fine for starting and evaluating what shape it is in.

There are several lubricant choices you can make with this period vehicle (no smog controls being a plus). Has the engine been upgraded to a spin-on filter and has the crankcase ventilation system been serviced?

 

The best oil is whichever your favorite brand recommends. Ask them.

For a first start up like this, the oil will usually be drained fairly soon anyway, so no need to spend money on synthetic. It may not even start, or it may have bad oil pressure. Get the good stuff when you know it will run and there aren't any issues. Simply to see if it will start and run it for a short time, just about any oil will do.

I've never heard of oil galleys being mis-drilled. It's usually cam bearing wear and / or the quality of oil available and / or poor maintenance that eventually resulted in loss of oil to the top end. A rebuild and modern oils will eliminate that problem.